I'm thinking about a general way for classification in a.i. (in a preliminary stage) and i examined the notions "abstract" and "real/concrete".
I thought that the basic difference from the side of the consciousness is that "abstract" notions are those that we haven't experienced in the real world and are created by the mind, and "real" are the objects that we encounter around us (very roughly spoken).

So the notion of an "apple" is a mental image of the real object apple, but
"measure" is an abstract notion, there is no actual "measure" in the real world but we derive the notion of it after making comparisons between objects. The abstract element between the comparisons is the measure. (Let's not complicate the discussion by thinking about actual objects that may have been used for measuring in the first place and may provided the term for comparisons subsequently).

In Greek (my native language) the word for "abstract" is apheresis, "αφαίρεση" which really means "subtraction". I tried to think how that notion may be derived. I thought about death. When someone dies he is no longer between us. He is subtracted (in a way) from the world. So this is my question: Do you think the term "abstract" or the term "subtraction" is derived when people thought about the process of death or other forms of elimination (like when you eat something or when you give something to someone else), so ultimately this notion is based on experience?

I'm not referring to the philosophical term of abstraction which probably appeared very late following numerous introspective motions after progressions in the language and society organization.

Do you believe to the platonic idea of the forms or that the mind/language/society/history creatively produce and develop generalized depictions of relations encountered in the real world and in experience?

Should i equip my a.i. model with a pre - knowledge, or an "intelligence" should be able to create prototype classification/categorization based only on data/stimuli. (i understand though that language/thinking/intelligence is not created by individual atoms in nature)

The Notion (of something) is people's generalised enduring image of
it, which has taken shape and is acquired in the course of social
practice, held in the mind without the immediate action of the thing
upon the senses (as in immediate perception).

To the ordinary non-philosophic understanding, the notion is given
immediately in experience; to empiricism, the notion is nothing but an
"abstract universal" denoting a collection of individual things
possessing a common property; to metaphysical philosophy before Hegel,
the Notion is given by intuition or is a self-evident truth arrived at
by introspection, and for subjective idealism the Notion has no
referent in the objective world. {...}

1 Answer
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"Abstract" is usually contrasted not with "real" but with "concrete", there is no logical problem with reality of abstractions. As for aphairesis we owe the meaning to Aristotle, who did derive it from subtraction:"In the context of mathematics, Aristotle uses the term "abstraction" (aphairesis) to refer to the act of ignoring or disregarding matter and change from perceptible objects in order to isolate their specifically mathematical characteristics as distinct objects of thought". See Smith's Aristotle on Abstraction.

Roughly speaking, Aristotle thought of concrete things as quivers of properties, for example a bronze ball has bronzeness, roundness, firmness, etc. By taking (subtracting) all geometrically irrelevant arrows , like bronzeness, firmness, etc., out of the quiver we are left with "abstracted" ball of geometry. Both Plato and Aristotle are realists about universals. But Plato ideas are free floating and people have to encounter them in their purity prior to birth, and then unforget. Aristotelian forms, on the other hand, do not manifest separately from the matter that embodies them, and we obtain our concrete quivers from ordinary experience, not from mystical anamnesis. This would be the simplest realization of your proposal, assuming that the properties-arrows in objects-quivers are directly accessible to us. Interestingly, Aristotle also believed that thinking and memory are based on mental images (phantasma), that are either direct "impressions" on the soul or are produced from those by manipulation processes like abstraction. See more on Aristotelian realism in Franklin's paper.

In modern times Aristotelian realism was revived and expressed in much more subtle and elaborate form by Husserl, who gives a very detailed and sophisticated account of abstraction and other mental manipulations in Ideas for Pure Phenomenology. In particular, he describes in detail our faculty of ideation, which is analogous to sensation of concrete objects in providing some immediate experiences of universals/forms of those objects (without Aristotelian process), or eidoses (essences) as he calls them. In fact, ideation and sensation are seen two abstractions of our unified immediate perception. On Husserl's account the path from ideated eidoses to higher universals is much more complicated, and involves free variation in imagination and so-called eidetic reduction. I am not sure how much of his elaborations can be realistically modeled in AI.